#a3{
    width: 100px;
}
.b2{
    width: 300px;
    height: 100px;
    background-color: aqua;
}
.b3{
    color: blueviolet;
}
.b4{
    width: 200px;
    height: 200px;
}
.pink{
    background: pink;
}
.b6{
    width: 30px;
    position: absolute;
}
#d2{
    width: 1200px;
    height: 300px;
    padding: 0;
    margin: 0;
}
#d2 li{
    float: left;
    transition: all 500ms; /*过渡 用于图片展开时的效果*/
}
#d2 li img{
    width: 300px;
}
#b8{
    width: 300px;
    height: 300px;
    background-color: royalblue;
    overflow: auto;
}